Inclinometer



Nov. 23 1926.

J. M. DUNLEA INCLINOMETER Filed Jan. 50, 1920 Patentecl Nov. 23, 1926.

' UNETED"STATES PATENT OFFICE.

JOHN M. DUNLEA, or LOS ANGELES, CALIFORA, nssrenon or ONE-TWENTCETH r WILLIAM wnmsrnm, or Los A1\TGELES, CALIFORNIA.

INCLINOMETER.

' pp 1ication filed January 30, 1820. Serial No. 355,138.

ely inventipn is an instrument primarily designed for use on aeroplanes, and adapted to accurately indicate either fore and aft or lateral tilt; and also arranged to indicate acceleration and retardation, as well as curvature in the line of flight, of the aeroplane. f

Inclinometers have been heretofore constructed which include a support 'arranged to tilt with the aeroplane, and a pendulum designed to maintain a perpendicular posi tion, so that the relative movement between the support 'and pendulum would show approximately the tilt of the aeroplane. y

Such devices are inacc'urate however, since acceleration or retardation .accompanyre and att tilt of tne aer0plane, has

of the support and peiedulum, due to the 'nertia or" the letter; and similarly, varia- .ions in the relative position of the sup- 3ort and pendulum' have 'occurred during ateral ment of the pe'ndulum through the centrfugal :torce produced by the turning movement of the aeroplane, which turning movef ment is incident to a lateral tilt of the 1na chine.

As a result, the relative position of the support and its pendulum has not given a rue indication of the tilt of the aeroplane.

In Order to overcome the above difliculties, I provide a device comprising essentiaily a support fixedfor tiltin'g movement with the aeroplahe,and two members' sup-, ported therehy so that the support is free v for independent movement relative to the The members are in respectiv wmbers turn errangcd, so as to tend to different de- 'rees, to maintain perpendicular positions, d as a result, acceleration or retardation the machine, and also centrifugal f0rce reduced by turning movement during lat ral tilt, will shift the respective members o different degrees, so that the difierence in the position of the support with respect to the twh members, wiil give an accurate basis for determining thetrue tilt of the aeroplane. The diflerence in the positions of the two members with relation to thesupport, also indicates acceleration or retardation of the machine, and turning of thesame.

d variation in the relative movement tilt 01" the niachine,due to the move In the practical embodiment of the in- Vention set forth,

F ig, 1 is airont elevation of the device.

Fig. 2 is a vertical longitudinal section, partly broken away.

Fig. 3 is a section on the line 33 of Fig. 2L

Fig.

The supporting element of the device,

4 is a top plan view of the pendulums.

which is fixed relative to the aeroplane, is

shown as casing 10, having front opening 11 provided with a transparent plate .12. A filling port having closure cap 13 is also provided in the casing, and through this port the casing is preterably filled with a liquid 14., which is non-freezihg and not too mobile, as tor example,a niixtnie ot' alcohol and glycerine. 1

A ring 16 is mounted in the casingby trunnions 15, so that its aXis is in a normally horizontal transverse plane, and an annular band 17 is journaled in ring 16 by means of trunnions 18, so that its aXis is in a.normally horizontal longitudinal plane relative to the casing. The bottom of band 17 is weighted as shown at 17 and the band llllllsf01lls a pendulum having its pvot at the centers of ring 16 and band 17, and adapted to maintain a perpendicular position irrespective of fore and ar"t or lateral tilt of casing 10 with the aeroplane.

A perpendicular rod 19 depends from the top of band 17, and may'have a buoyant ball 20 fixed thereon. At the end of rod 19 a univrsal joint is formed between the same and a depei1ding sleeve 2 1, said joint having'its center concentric with the pvot of pendu lum band 17, and tt mprising a pivot pin extending transversely through rod 19, with Arcuate bands 27 extend upwardly from weight 25, both front and rear,fand prefer"- ably at the respective sides of band l'7, the

space between the upper ends of the front and rearlhads providing for movement of line 28 extending across the inner pendulum formed by weighted sleeve 24, independent 01" the outer pendulun formed by band 17, without the liability of bands 27 striking rod 19.

The outer pen-dulum, comprising band 17, is so weighted as to move relative to the liquid within the casing, without said liquid aflecting the movement of the pendulum to any extent, and said freedom of movement is enha ced by the buoyant effect of ball 20. The inner pen=;luhnu, en the other hand, is ot lightcr we nt, so that its movement relative to the liql will be controlled to an apnreciable extent by latter, and

1. said control may le increaseo oy providing a retarding disc 28 upon sleeve The bands 17 and 27 are preferably provided with scales both front and rear, and graduated upwardly and downwardly from zero; and when the a roplane upon which the device is mounted, is flying without r"ore and att or lateral t' lt, so that casing 10 is upright, the zeros ot scales 17 and 27 will coincide,with a horizontal center line 29 provided at opening 11, and the scale bands will also be parallel to the vertical center the sight opening of the casing.

When the aeroplane and casing fixed thereto, tilt toro and att, and if there is no acceleration or retardation, the two pendulums maintain a perpendicular position, so that either upper or lower coinciding scale marlgs ot bands 17 27 appear opposite the harizontal center line ot opening 11, thereby registering the degree of tilt of the machine by said graduations, and'also denoting the absence of acceleration or retardation, through the cincidence ot the scale markings of the two bands 1727.

Normally, however, a foro and aft tilt will be accompanied by either acceleration or retardation ot the machine, so that the pendulums will tend to swing either rearwardly or :t' nwardly from the perpendicular, and therefore not accurately register the degree of tilt. But since the out-er pendulum is arranged for greater freedom of movement than the inner pendulum, as previously described, the pendulums will swing to different degrees, so that the difierence between their scale markings with relation to the horizontal center line of the sight opening of casing 10, will indicate acceleration or retardation as well as tilt, and will also form a basis for readily computing the amount of acceleration or retardation and tilt, the calibratiori of the instrument being predetermined;

In similar manner, in the case of lateral tilt unaccompanied by turning movement of the} aeroplane, the scale bands 1727 Will assume an equi -angular position wit relation to the vertical center line 28 of the sight opening ll; The instrument will thus accurately show the angle of lateral tilt, and will also denote the absence of turning movement of the aeroplane by the parallel ism of the bands. Y

In the normal case, however, since bank ing of the aeroplane will cause turning movement thereot, the pendulums will tend to swing laterally through centrifugal force, and here again the difference in the degree of swing ot the respective pendulums, due to the difference in their freedom of movement and tendency to remain perpendicular, will cause a difierence in the relative angular positions of the two bands 1727 to the vertical center line 28, so that said angular difierence will indicate both turning movement and lateral tilt.

It will thus be seen that I have provided a simple but elficient and accurate instrument for showing not only fore and att and lateral tilt or" an aeroplane, but also acceleration and retardation thereof, as well as turning movement when banking.

lt will also be noted that the arrangement of the graduated bands with scale marking on both the front and rear portions of the same, together with the construction of the pivotal mountings for the pendulums, permits of bands 1727 being seen through the sight opening of the casing, even though the aeroplane may pass through involved lines of flight.

The specific construction which has been described is but one practical embodiment of the device, and it will be readily apparent that various changes in the construction arran 'ement and combination of 7 b 7 parts, muy be maoe without departmg from the scope of the invention,

What is claimed is:

1. A device of the character described comprising a support, pendulum members having tree pivotal suspension from said support se as to assumeperpendicular positions, one of said members being adapted tor substantially' free swinging movement beyond the perpendicular in response to accelerated or retarded movementot' said support, and the other of said members having means for partially retarding tree swingihg movement thereof relative to the fir st member and beyond the perpendicular in response to accelerated or retarded movement of the support, whereby an angular diiierence is created between said members during acceleration or retardation of said support, said angular difference varyingin accordaricewith said accelerated or retarded movement, and cooperating means for said members for indicating. said angular= difference.

y 2. A device' of the character described comprising a casing. adapted to receive a hound, members p1voted in said casing so as to assumeperpendicular positions, one ot sai d members being adapted for fr'ee swinging movement through the liquid beyond the nerpendicular in response to accelerated cr retarded movement of the casing, and the other of said members having 7 means adapted to be impinged by the liquid for mrtiaiiy retarding free swinging movement Aid member relative to the first member ii whereby an angie Will be formed bet\ en the members during acceleration or re mdatzon ot the cas1ng, said angie vary1ng in acc0rdance with said accelerated or retarded mov ment, and scale markings coopwit both ot said menrbers tor indid a liar dinerence. device of the character desmribed coinprisingr a casing adapted to receive a liquid, v.eighted members pivoted in the casing so as to assume perpendicular positions, a biioyant element in said liquid upon one ot the meinbers above its pvot to permit free swinging movem nt o:" said member beyond th perpen ;licnlar in response to accelerated or -re arded movement ot the. ezsing, the other ot said members having means for 1:;arrially retarding tree swinginp; mo vement there0t relative to the first member and beyond the perpendicular in response to aecelerated or retarded movement ot the casing, whereby an angie Will be formed between the members duringacceleration or retardation ofthe casing, said angle varyihg in accordance with said accelerated or retarded movement, and cooperating means tor said members indicating said angular difference.

A device of the character described comprising a support, an annulus pivoted therein and having a transverse normally horizonal ans, second annulus jonrnaled in said first annulus and having a longitudinal normally horizontal axis, said second annulus being weighted at one side of its axis so as to form a pendulum, a universal joint supported by said pendulum annulns at the ntersection or" said axes, and a second pendulum suspended from said universal joint within said pendulum annulus, one of said pendhlnms being adapted for substantially fre 'swinging movement beyond the per pendieular in response to acceleratedor retarded movement of the support, and the other of said pendulums having means for partially retarding free swinging movement thereot relative to the first pendulum and beyond the perpendicular in response to accelerated or retarded movement of the support. Whereby an angular diflerence is created between said pendulums during ac celeration or retardation of the support said v angular diiterence varying in accor ance with said accelerated or retarded movement.

5. A device of the character described comprising a support, an annuls pivoted therein andhaving a transverse normally horizontal axis, a second annulus journaled in said first annulus and having a longitudinal normally horizontal ans, said second arinulus beingwighted at one side ot its axis so as to forma pendulum, a rod este ing inwardly connected to the upper D01 of said pendulum annulus, aunivers carried by said rod at the intersect1on ot said axes, a second penduium suspended from said universal joint within said pende.- lum annulus, an arcuate band fixed to said second pendulum and 1y1ng parallel to sa1d pendulum annulus when the pendulums are perpendicular, a vertical and horizontal sight line on said support cooperating with said arcuate band and said pendulum annu lus, and cooperating graduati0ns on said r arcuate band and said penduium annuius, oneot said pendulums be1ng adapted tor s1 1bstantiall free swinging movement. be-

eratod or retarded movementotthe support,

and the other of said pendulums having means Ior part1aily retardmg tree swmg1ng n1ovement thereo:t relative to the first pendu nm and beyond the perpendicular in re- 6. A dev'ce of the character described romprising a support, an annulus pivoted therem on normally horizontal transverse and longitudinal axes, said annulus being weighted at one side of its axes so as to form a pendulum, a universal joint supported by said pcndulum annulus, a pendulam susg 3ended from said universal joint Within the pendulum annulus, one of said pendulums being adapted tor substantially tree swnging movement beyond the perpem dicular in response to accelerated or retarded movement of the support, and the other of said pendulumts having means tor partially retarding free swinging movement thereot relative to the fi*st pendulum and beyond the perpendicular in response to accelerated or retarded movement of the support, where by an angular difference is created between said pendulums during yaccelerationor retardation of the support, said angular difference varying in accordanee with said accelerated or retarded movement, and co operating means on said pendulums for indicating said angular difference.

7. A device of the character describedcomprising a support, an annulus pivoted therein on normazlyhorizontal transverse and the perpendicuiar in response to aerel longitudinal axes, said annulus being weighted at one side of its axes so as to form a pendulum, a universal joint supported by said pendulum annulus at the intersection of said axes, a pendulum suspnded from said universal joint within said pen dulum annulus, an arcuate band fixed to saidsecond pendulum and ly1ng parallel to the pendulum annulus when the pendulums are perpendicular, and cooperating graduations tor said areuate band and said pendulum annulus, one of said pendulums being adapted for substantially free swinging movement beyond the perpendicular in response to accelorated or retarded movement ot the support, and the other of said pendulums having means for partially retarding free swinging movement thereof relative to the first pendulum and. beyond the perdendicnlar in response to accelerated or retarded n'iorement of the support, whereby he arcuate band and the pendulum annulus vill he moven different distances in a longitudinal olane and Will form an angular difin a transverse plane during acceltorenev erated or retarded movement of the support.

8. A. device ot the character described comprising two members pivoted on axial hearings and each weighted at one side of Ets pivotal axis so as to form a pendulum assuming a perpendicular position with minimum f ictional resistance at its pivotai bearing, one of said pendulums being adapted for substantially free swinging movement beyond the perpendicular in response to accelorated or retarded movement of the device, and the other of said pendulums having means tor partially retarding free swinging movement thereof relative to the first pendulum and beyond the perpendicular in response to accelerated or retarded movement of the device, whereby an anguiar difference is created between the pendulums during acceleration or retardation ot the device, said angular difference varying in accordance with said acceleration or retardation, and cooperating means for said members indicating said angular difference.

9. A device of the character described oomprising a support, members universally pivoted to the support so as to assume perpendicular positions the universal bearings ot said members each having a fixed relation to the support, one of the members being adapte: for substantially free swinging movement beyond the perpendicular in response to accelerated or retarded movement of the support, and the other or" the members having means for partially retarding free swinging movement relative to the first member and beyond the perpendicular in response to acclerated or retarded movement o:t the support so as to create an angular di-eren0e between the members during acceieration or retardation ot the support, said angular difference varying in accordance with said acceleration or retardation, and cooperating means for said members indicating said angular difierence.

n witness that I claim the f0regoing have hereunto subscribed my name this 23rd day of January 1920.

J. M. DUNLEA. 

